The photochemical and spectroscopic properties of the isomeric retinals, synthetic analogs, the visual protein rhodopsin, and synthetic pigments will be examined. In particular, we are interested in the protein-chromophore interactions in rhodopsin and the effects of these interactions upon the photoisomerization of 11-cis retinal have been examined. The nature of the protein-chromophore interactions in rhodopsin will be investigated using high resolution infrared spectroscopy. Difference spectrum obtained by subtraction of infrared spectra of opsin from rhodopsin and of rhodopsin from several of the bleaching intermediates obtained upon low temperature photolysis will be recorded. Information obtained from infrared and photochemical studies of synthetic pigments, i.e. isorhodopsin and 9,13-isorhodopsin, should be of value to the understanding of the chromophore's environment.